13种负载CO2醇胺水溶液体系的高温氧化降解特性OA

[Purposes]Oxidative degradation of alkanolamine absorbents significantly limits the economical viability of CO2 capture process.A detailed investigation into oxidative degradation behav-ior of alkanolamines with different molecular structures is crucial for the screen of highly stable absor-bents,the optimization of process parameter,and the elucidation of degradation mechanisms.[Meth-ods]In this study,the oxidative degradation characteristics of 13 CO2-loading alkanolamines were systematically examined under conditions of 120 ℃ and 1.0 MPa with O2.[Results]The experimental results reveal that the steric hindrance effect in the alkanolamine molecular structure is a key factor in-fluencing oxidative stability.Notably,N,N-dimethylethanolamine and 2-amino-2-methyl-1-propa-nol exhibit superior oxidative stability(with amine loss ratios of 9.5%and 2%after 8 h degradation,respectively)owing to the strong steric hindrance around their amino groups,significantly lower than the 26.2%loss for monoethanolamine.The oxidation degradation process reduces the alkalinity of the system,and the degree of alkalinity loss is basically the same as that of amine loss.The pH of the so-lutions generally decreases by 1%-7%,viscosity decreases by 0.6%-16%,conductivity increases sig-nificantly,and surface tension declines.These physicochemical changes are primarily attributed to the accumulation of organic acids and the cleavage of alkanolamine molecular chains.Furthermore,for-mate and oxalate are detected in all degraded alkanolamine solutions,while acetate formation is strongly correlated with the presence of ethyl side chains in the molecular structure.In addition,dur-ing the oxidative degradation of primary alkanolamine at high temperatures,its primary oxidation prod-ucts undergo further intermolecular condensation reactions to generate more complex secondary degra-dation products.